1. Field of the Invention
The present invention relates to endoscope technology and more particularly, to an endoscopic image pickup device that provides multiple illumination directions.
2. Description of the Related Art
A regular endoscope, either for industrial or medical application, generally uses an image pickup device (a combination of a tube, a lens and a light source) in the front end of a tubing for illumination and image pickup. When picking up images, the light source provides illumination, and the lens picks up the images. When inserting the tubing into the inside of an object to the target to be examined, the light source illuminates the target, enabling the lens to pick up the images of the target and to transfer the images to a display screen for display. Thus, the user can observe the images displayed on the display screen to check the target that is not directly visible with the bare eyes.
In the aforesaid conventional endoscope, the illumination direction of the light source in the front end of the tubing is parallel to the image pickup direction of the lens. Therefore, under normal conditions, the area illuminated by the light source covers the image pickup range of the lens, enabling the lens to pick up images effectively. However, if the lens is a wide-angle lens, the image pickup range will be greater than the illumination range of the light source. In this case, the center area of the fetched image will be relatively brighter than the border area. Thus, the image picked up from a dark area may be no clear.
Further, when the image pickup device of the aforesaid endoscope is operated to pickup side images, a side view attachment may be used. A side view attachment for this purpose generally comprises a reflector and a transparent window located on one lateral side. The reflector reflects incident light passing through the transparent window onto the lens for image pickup. However, as the illumination direction of the light source in the endoscope is parallel to the image pickup direction of the lens, the light emitted by the light source falls directly upon the reflector and then reflector reflects the light onto the target at first, and the light reflected by the target will then be reflected by the reflector onto the image pickup lens. Under this operation manner, the coating quality of the reflector must be excellent to assure image clarity. Further, the reflective surface of the reflector must be constantly kept clean, any contamination of the reflective surface of the reflector will cause scattering of light, affecting picture quality.